Commonly-assigned U.S. Pat. No. 4,938,370, issued July 3, 1990, and U.S. patent application Ser. No. 465,301, filed Jan. 23, 1990, illustrate various embodiments of a tamper-indicating plastic closure which has proven highly resistent to tampering or the like, and which is configured to facilitate economical, high-speed manufacture. Notably, this type of tamper-indicating closure is configured to provide two modes of tamper-indication for enhanced effectiveness.
In a first mode of operation, inwardly extending flexible tabs of the closure pilfer band are arranged to extend angularly upwardly into contact with the annular, locking portion of a container. During closure removal, this arrangement effects at least partial, readily visually discernable detachment of the pilfer band from a skirt portion of the closure by fracture of a frangible connection therebetween. In a second mode of operation, the flexible tabs are positionable to extend angularly downwardly, and thereby cooperate with an annular interference bead of the pilfer band to decrease the effective internal diameter of the pilfer band. Again, this effects the desired fracture of the frangible connection attendant to closure removal from the container.
In accordance with the above disclosures, a frangible connection between the pilfer band and the skirt portion of the closure is preferably provided by a plurality of circumferentially spaced, frangible bridges which extend between the inside surfaces of the skirt portion and the pilfer band. A circumferentially extending score line distinguishes the pilfer band from the skirt portion, with the score line extending partially into the frangible bridges. This type of frangible construction is illustrated in commonly-assigned U.S. Pat. No. 4,418,828.
As will be appreciated, in order to provide the desired tamper-indicating function, a closure of the present type must be manufactured so that the frangible connection between the pilfer band and the skirt portion does not fail or fracture during high-speed application of the closure to the container. Thereafter, the closure should consistently and reliably fracture at the frangible connection attendant to partial or complete closure removal. The present invention has been found to desirably abate premature detachment of the closure pilfer band by fracture of the frangible connection during automatic high-speed application of closures to containers.